Blade sharpening devices are known which have two or more pairs of grinding rollers or wheels located in mutually facing positions with their respective lateral grinding surfaces in adjacent relation.
The cutting blade is sharpened by being interposed between the two rollers with the blade edge contacting the grinding surfaces and causing the rollers to rotate about respective parallel axes with opposite directions of rotation.
EP 2,014,414 discloses a knife sharpening device that comprises two endless abrasive belts which are mounted in a closed-loop configuration to a drive unit comprising two respective pairs of motorized pulleys in such arrangement as to cause two active branches of the abrasive belts to be in mutually facing and converging positions, a gap being formed therebetween, in which the knife blade to be sharpened may be inserted and sharpened.
The distance between the two abrasive belts may be adjusted by adjusting means to fit the blade size.
Nevertheless, such common solution still suffer from certain drawbacks.
A first drawback consists in that rigid grinding rollers provide a cutting blade having a sharp-edged profile, whose quality is not always acceptable.
Furthermore, these solutions are of no use for ceramic blades, due to the greater fragility of the latter.
An additional drawback of these known solutions is that, during sharpening, the blade has to be pressed against the roller, and is thus heated, which may cause loss of hardness of the material, usually steel.
Yet another drawback is that the top-to-bottom rotation of the grinding surfaces of the rollers causes burr build-up, that forces frequent process stops for burr removal.
A further drawback is that prior art sharpening devices are mounted to fixed shells which set an operating position thereof, and introduction of the blades to be sharpened from both sharpening sides between the grinding members, for better sharpening, requires users to repeatedly move around the device for direct access to each side.
Another drawback is that, during blade sharpening, the user that holds the blades may inadvertently introduce them through an excessive distance between the grinding members, with the blade handles possibly contacting the latter and being damaged by their fast rotation, as soon as contact occurs.
Furthermore, prior art sharpening devices have no protection means, which might prevent the user from accidentally contacting the grinding members also by their hands during operation.